Stimulation may be applied to target nerve tissue in the brain or spinal cord to treat a variety of clinical conditions. According to one technique, a set of efficacious neurological stimulation parameters are determined, the set of parameters is entered into the system, and the system is used to stimulate, either electrically or chemically, the target nerve tissue according to the set of parameters to treat a condition.
For electrical stimulation, typically, an implanted pulse generator (IPG) transmits a pulse of efficacious electrical energy to an implanted electrical stimulation lead according to the set of parameters and, in response to the pulse, the electrodes of the implanted stimulation lead deliver the electrical energy to the target nerve tissue to treat the condition. For chemical stimulation, typically, an implantable drug pump transmits a pulse of efficacious drugs through a catheter according to the set of parameters and, in response to the pulse, infusion ports of the implanted catheter deliver the chemical dose to the target nerve tissue to treat the condition.
However, there exists a certain population of patients with conditions that are intractable to standard therapies. For example, some patients with neurodegenerative diseases or trauma such as cerebral infarct or spinal cord injury may experience pain or undesirable movements such as spasticity or dyskinesia that are not responsive to stimulation of the cortex or spinal cord. As another example, some patients with chronic pain in multiple locations may not obtain full relief using previous stimulation techniques. Alternative stimulation methods are desirable to treat the population of patients with conditions that are intractable to standard therapies.